A group III nitride compound semiconductor light-emitting device is known as a light-emitting diode which emits a light having a color ranging from blue to green. Such a group III nitride compound semiconductor light-emitting device is used also as a light-emitting diode which emits light having a wavelength shorter than the visible light (near ultraviolet to ultraviolet).
A group III nitride compound semiconductor light-emitting device which emits short wavelength light has been heretofore known, but such a light-emitting device has recently been required to have a higher light-emitting efficiency and output.